Onyx is a kind of chalcedony that’s usually black or darkish brown in coloration. It’s a standard gemstone that’s typically utilized in jewellery and different ornamental objects.
Onyx is fashioned when silica-rich water seeps into cracks and cavities in rocks. Because the water evaporates, the silica crystals develop and type a strong mass. The colour of onyx is set by the presence of impurities, reminiscent of iron or manganese.
